I have searched all the archives on everything
I could find on Headers, and specifically, Primary Tube Size. There seems to be some controversy, so I really would like to get the opinions of those of you in the know. I fully understand that if the header tube diameter is too large that it will affect torque in a negative way, and it seems that most of what I have read, says that going with 2" primary tubes is too big for typical 396 CI engines.

OK, now for my question. I will follow with the specs on my engine, so hopefully this will help.

I need to replace my headers due to the passenger side getting rubbed,dented and worn too thin. I have Hooker Super Comps with 2" primary tubes and 3.5" collectors. Please have a look at my specs and help me understand if I should stay with 2" or if I should go with 1.75" or even 1.875" primary tubes. I assume that if I stay with Hooker Super Comps, that they will bolt right up to my pipes ? and if I go with a different brand, my pipes will need to be either cut or extended and new flanges welded on ?

Sorry to be so long winded, but I really want to get the right Headers for optimal performance, and of coarse fit. Here are the specs.
Thanks a bunch smile.gif Gaz

-69 Chevelle SS
-454 CI LS6 Short Block
-10:1 CR Forged LS6 Pistons
-Isky 620 Solid Roller 248/248 @.050.620/.620lift
-Performer RPM Intake
-Performer RPM Rectangle Port Heads
-Holley 950 HP
-MSD 6AL
-Mallory Performance Coil
-2" Hooker Super Comps 3.5 collector, 3" with
H-pipe thru 40 series Flowmasters and 3"tails
-Richmond 5 speed
-Richmond 308 Posi
-150 shot NOS (which I have yet to spray)
-Upper control arms fitted w/Anti-hop system

I use 1.75",but you could probably get away with 1"7/8 tubes and 3" collectors. I like dynomax coated headers also,going on 3 years and still look good.

Ditto,
I think 1 7/8 & 3" collector would be about ideal.
My second choice would be 1 3/4" for mostly street

Bob,

I noticed when I did a search, you spoke well of the Hooker Super Comps. Have you had a better experience with the Dynomax since ? If I go with the Dynomax, I will probably need to take the car to a exhaust place because I'm would think that the position where the collectors bolt to the pipes would be different ? Do you think that 2" primary tubes are too big for my engine specs ? I would assume this is the case, because you and Mike both suggest the 1.875 I guess I would like to know what your reasons are.

Thanks Guys, I really do appreciate it!

Gaz graemlins/waving.gif

Gaz, get the ceramic Dynomax's ( or the paint-ur-own Summmit's at under $100!), and a Hedman, or similar, X pipe ( 3" Inlet X 3" or 2.5" outlet). Then the muffler shop can splice in the X and finish the system.

Here's a great discussion with the equation I was looking for.

http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=018070

I liked the Hookers for fitment/installation,then I had to drive the car, the collectors hang down way too low,I had the tubes almost smashed flat on the bottom. I was using the 2" tubes and couldnt get into the 11's,,,I think my best was 12.04-12.05, I did several changes though thru the winter 2-3 years ago...headers to 1.75",new distributor,and carburetor and netted me a 11.78,,,so which played the biggest part I havent a clue. I do like the dynomax headers though,they look good and fit just as well as the Hookers and don't hang down near as low. I also run 3" head pipes to 3" dynomax ultraflo welded ovals with dumps at the rearend.

My 2 cents with your low gear, I
would go with the smaller tubes. If
you had a thought of going with
a bigger gear I would raise the tube size.
I have a 69 Chevelle that weighs 3770 with
me in it & pretty much the same stuff has
you but with a 4.56 gear & I run 2 1/4 tube
( which I wish I had put 0n 2's ) & my best
pass so far is 11.06.

www.headerdesign.com (http://www.headerdesign.com)

88,200 Xs (port area in sq. in.) divided by the displacement of a single cylinder should equal the "peak torque RPM".

You'll want to size the header tubes to the "peak torque RPM" of your engine combo to maximize their efficency.

So, let's assume that the peak tq RPM of your engine combination is 4500rpm. Let's also, for ease in calc., use .050 as wall thickness in a 2" header.
The area of the tube would be 2.83sq in X 88,200 = 249946 divided by 56.7 = 4408rpm. Moving up to a 2.125 tube would work best in a combo that "peak torqueRPM" occurs at 5000. A 2.25 tube will peak @5650rpm.

When your ready to put on the pipes, give Albany Wheel and Exhaust a call. I take them all my exhaust business. They have put exhaust on my 69 Camaro, 91 burb, 86 and 87 Monte SSs, 68 SS396, 99 burb, 88 K5 Blazer, and 87 SWB 4x4. They do good work and are fellow gear heads, Mostly dragracing MOPAR nuts but they actually just got a couple cool old GMs (66 Goat and 55 Chev). They are on Geary just south of 9th st. Family owned business-3 generations :cool:

BTW if you want to look at a pair of Hedman Elite shorties, let me know, I can throw a new one in the rig and bring it to work. (C-shift 5p-5a) May actually be selling them as they may not work on my 540.

Jeff,

About three months ago, I actually had Mike at Albany Wheel and Exhaust do my system from the collectors back and he did a real nice job. He did what he could to fix the lowest tube on the pass side header, and at the time told me they were getting sort of thin but thought I could get another year or so out of them. Well, If I had not of rubbed em on something, I probably would of been OK. I wish I would have put the new headers on at the same time graemlins/clonk.gif

Thanks for the offer to see the shorties, but I think I want to stay with a full length header that tucks up a wee bit more than these HSC's.

Gaz

In your car specs you have a 454...right?
But your note says 396???
I assune it's a 454.
In my opinion, 2" headers are fine.
And don't forget that Hooker also makes Comp headers that probably fit better, and don't hang down as much.
One more important thing, how well would a 1.75" header match at the exhaust port? If it covers part of the port opening, it's a bad deal.
Something to check.
Ron
(fellow Oregonian)

Thats the headers I had that hung down too low Hooker comps 2" tubes.

Ron, it is a 454. I only made mention of a 396 because there has been a lot of controversary about 2" headers being way too big for them.
I guess I am trying to understand what displacement one should step to the 2" tubes for optimal performance.

All, I have read your replies, and done some research as well. Although I still am hearing one side for 1.75"-1.875" and the other side for 2" I have chosen the 1.875 tubes for my engine combination.

Once I get them installed, I will post my experience...

Thanks graemlins/beers.gif Gaz

Hey Gaz,

What 1 7/8" headers are you going with? I didn't think there were to many manufacturers of those. Hooker has there Super Comps, but the cost of those with the ceramic coating is up around $600! :eek:

Another option is to use the 2" headers and install a set of Flowmasters "Pulse Tech" 4-2-1 collectors. This is what I did. It should help the low/mid range power when using the larger tubes (2"). Just a thought. smile.gif

Darren,

After talking to the guy that did my exhaust from the collectors back, and learning from Hooker that the SC 2217 which is the 2" tube and what I have now, I went with the SC 2250 1.875" tube. According to Hooker, the 2250 was designed to be built using the same Jig as the 2217, so they should be very close to the same mounting location as my pipes are now. I know that they will hang lower than I really want, so I will need to be extra careful not to drag em.

Ya, they are expensive :eek: but I talked to a lot of folks that say you get what you pay for.

I hope I made the right choice graemlins/thumbsup.gif

Gaz and his expensive new headers...